Data management information obtaining method for obtaining data management information including information concerning part of data areas as information concerning a pseudo area

ABSTRACT

On an information recording medium, a recording area is divided in a plurality of data areas, and data is recorded on each of the data areas. In response to a request for obtaining data management information concerning a recording of the data recorded on each of the data areas, a plurality of predetermined data areas among the foregoing data areas are regarded as a predetermined pseudo area, and the data management information including information concerning the predetermined pseudo area is obtained.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a data management informationobtaining method, an information reproducing device, a data managementinformation obtaining program, and a recording medium, and moreparticularly, to a data management information obtaining method forobtaining management information concerning a recording of data recordedon each of data areas divided in a recording area of an informationrecording medium, an information reproducing device using the datamanagement information obtaining method, a data management informationobtaining program for causing a control computer of the informationreproducing device to perform the data management information obtainingmethod, and a recording medium storing the data management informationobtaining program.

2. Description of the Related Art

Recently, personal computers have been provided with improved functions,such as a function of dealing with AV (Audio-Visual) informationconcerning music and video images. Since the AV information amounts to aconsiderably large extent, optical discs, such as a CD-R and a DVD+R,have come to attract attention as information recording media forrecording such AV information. Further, as such optical discs havebecome inexpensive, optical disc devices as information reproducingdevices have become widespread as peripheral devices for a personalcomputer.

Recordable optical discs, such as a CD-R and a DVD+R, adopt a filesystem conforming to a sequential UDF (Universal Disc Format) standard.In a recording area of such an optical disc, data is recordedsequentially in recording units referred to as tracks (or fragments forDVD+R). Further, a lead-in and a lead-out are added to an area composedof the tracks so as to form a session. Besides, hereinbelow, the term“track” is sometimes used for representing not only a track but also afragment, for convenience sake.

For example, a recording area of a DVD+R accommodates a maximum of 191sessions, and each of the sessions is capable of storing a maximum of 16fragments. That is, a DVD+R can include a maximum of 3056 (191×16)fragments. Besides, in a DVD+R, a lead-in of a second session and afteris referred to as an Intro, and a lead-out of a second last session andbefore is referred to as a Closure. Additionally, an area referred to asa session disc control block (SDCB) provided in a lead-in (or an Intro)of each session stores information concerning individual fragments ofthe session (hereinafter referred to as “fragment information” whichincludes a fragment number, and a start address and a final address ofthe fragment). Further, the SDCB includes not only the fragmentinformation concerning all of the fragments in the session, but alsoinformation concerning each of sessions preceding the present sessionwhich includes session numbers, a start address and a final address ofeach session.

In addition, a host device (e.g., a personal computer) needs informationconcerning a recording of data recorded on an optical disc prior toreproducing the data from the optical disc. Therefor, the host devicerequests an optical disc device to provide data management informationincluding information concerning sessions existing in the optical disc(hereinafter referred to as “session information” which includes thenumber of sessions included in a recording area) and informationconcerning tracks (hereinafter referred to as “track information” whichincludes the number of tracks included in the recording area and trackaddresses indicating recording positions of the tracks).

Then, for example when the optical disc is DVD+R, the optical discdevice informs the host device of the above-mentioned fragmentinformation in response to the request from the host device for thetrack information. Otherwise, when the optical disc is CD-R, the opticaldisc device obtains a response to the request from the host device forthe track information, based on track information recorded in an areareferred to as a program memory area (PMA).

However, for example when the optical disc is DVD+R, since the fragmentinformation is recorded in the SDCB of each session, the conventionaloptical disc device has to sequentially search the SDCBs of the sessionsdistributed in the recording area upon receiving the request from thehost device for the track information. Thus, the conventional opticaldisc device has an inconvenience of considerably deterioratedperformance, i.e., a considerably decreased response speed with respectto the request from the host device for the track information.

Thereupon, it is conceivable that the conventional optical disc devicemay obtain beforehand all the fragment information upon insertion of theoptical disc thereinto. However, as mentioned above, the conventionaloptical disc device requires a considerably long time to obtain all thefragment information; thus, there is an inconvenience of an increaseddisc mount time, which forces a user to wait for a long time to accessthe optical disc after inserting the optical disc into the optical discdevice. Further, as mentioned above, since the DVD+R can include 3056fragments at the maximum, it is difficult to store the fragmentinformation of all of these fragments, in consideration of memorycapacity.

SUMMARY OF THE INVENTION

It is a general object of the present invention to provide an improvedand useful data management information obtaining method, an informationreproducing device, a data management information obtaining program anda recording medium in which the above-mentioned problems are eliminated.

A more specific object of the present invention is to provide a datamanagement information obtaining method for quickly obtaininginformation concerning a recording of data recorded on an informationrecording medium in response to a request for obtaining the information,an information reproducing device using the data management informationobtaining method, a data management information obtaining programexecuted by a control computer of the information reproducing device toperform the data management information obtaining method, and arecording medium storing the data management information obtainingprogram.

In order to achieve the above-mentioned objects, there is providedaccording to one aspect of the present invention a data managementinformation obtaining method for obtaining data management informationconcerning a recording of data recorded on each of data areas divided ina recording area of an information recording medium as a response to arequest for obtaining the data management information, the methodincluding the step of obtaining the data management informationincluding information concerning a plurality of predetermined data areasamong the foregoing data areas as information concerning a predeterminedpseudo area in response to the request for obtaining the data managementinformation.

According to the present invention, the information concerning aplurality of the predetermined data areas among the data areas areregarded as the information concerning the predetermined pseudo area, tothe extent that the requested data management information is notadversely influenced; accordingly, unnecessary information does not haveto be obtained in response to the request for obtaining the datamanagement information. Therefore, the data management information canbe obtained in a shortened time Consequently, in response to the requestfor obtaining the information concerning the recording of the datarecorded on the information recording medium, the requested informationcan be quickly obtained.

Other objects, features and advantages of the present invention willbecome more apparent from the following detailed description when readin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a configuration of an opticaldisc device according to a first embodiment of the present invention;

FIG. 2 is a flowchart for explaining a data management informationobtaining method according to the first embodiment of the presentinvention;

FIG. 3 is a flowchart for explaining a data management informationobtaining method according to a second embodiment of the presentinvention;

FIG. 4 is a flowchart for explaining a process for obtaining the numberof sessions performed in the data management information obtainingmethod shown in FIG. 3;

FIG. 5 is a flowchart for explaining a process for obtaining the numberof tracks performed in the data management information obtaining methodshown in FIG. 3; and

FIG. 6 is a flowchart for explaining a process for obtaining addressinformation performed in the data management information obtainingmethod shown in FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

<<Embodiment 1>>

A description will now be given, with reference to FIG. 1 and FIG. 2, ofa first embodiment according to the present invention.

FIG. 1 is a block diagram illustrating a configuration of an opticaldisc device 20 as an information reproducing device according to thefirst embodiment of the present invention.

As shown in FIG. 1, the optical disc device 20 comprises a spindle motor22 for rotationally driving an optical disc 15 as an informationrecording medium, an optical pickup 23, a laser control circuit 24, amotor driver 27, a reproduction signal processing circuit 28, a servocontroller 33, a buffer RAM 34, a buffer manager 37, an interface 38, aROM 39, a CPU 40 (a control computer), a RAM 41 and so forth. It isnoted that arrows shown in FIG. 1 do not show all connections betweenthe elements, but only indicate representative courses of signals andinformation therebetween.

Besides, in the present embodiment, a DVD+R is used as the optical disc15, for example.

The optical pickup 23 comprises a semiconductor laser as a light source,an optical system, a light receiver, a driving system (a focusingactuator, a tracking actuator, a seek motor, etc.) and so forth. Thesemiconductor laser emits a light beam. The optical system introducesthe light beam to a recording surface of the optical disc 15, andintroduces a return light beam reflected on the recording surface to apredetermined light receiving position. The light receiver is placed atthe light receiving position so as to receive the return light beam. Thelight receiver supplies the reproduction signal processing circuit 28with an electric current (an electric current signal) according to anamount of the received return light beam.

The reproduction signal processing circuit 28 converts the electriccurrent signal output from the optical pickup 23 into a voltage signal;and according to this voltage signal, the reproduction signal processingcircuit 28 detects a wobble signal, an RF signal including reproductioninformation, and servo signals (a focus error signal, a track errorsignal, etc.). The reproduction signal processing circuit 28 extractsposition information and so forth from the wobble signal. This positioninformation is supplied to the CPU 40. Further, after applyingprocesses, such as an error correction process, to the RF signal, thereproduction signal processing circuit 28 stores the RF signal in thebuffer RAM 34 via the buffer manager 37. The focus error signal and thetrack error signal are supplied from the reproduction signal processingcircuit 28 to the servo controller 33.

According to the focus error signal, the servo controller 33 generates acontrol signal controlling the focusing actuator of the optical pickup23; and according to the track error signal, the servo controller 33generates a control signal controlling the tracking actuator of theoptical pickup 23. Both of the control signals are supplied from theservo controller 33 to the motor driver 27.

The motor driver 27 drives the focusing actuator and the trackingactuator of the optical pickup 23 according to the control signalssupplied from the servo controller 33. Additionally, according to aninstruction from the CPU 40, the motor driver 27 controls the spindlemotor 22 so that a linear velocity of the optical disc 15 becomesconstant. Further, according to an instruction from the CPU 40, themotor driver 27 drives the seek motor of the optical pickup 23 so as tocontrol a position of the optical pickup 23 in a direction of a sledgethereof, i.e., in a radial direction of the optical disc 15.

The interface 38 is a bidirectional communication interface with a hostdevice (e.g., a personal computer), and conforms to a standardinterface, such as an ATAPI (AT Attachment Packet Interface) and an SCSI(Small Computer System Interface).

The ROM 39 stores programs including a hereinafter-mentioned datamanagement information obtaining program described in a code decodableby the CPU 40.

The CPU 40 controls operations of the heretofore-described elementsaccording to the above-mentioned programs stored in the ROM 39, and alsotemporarily stores data and so forth necessary for the control in theRAM 41. Besides, upon application of power to the optical disc device20, the above-mentioned programs stored in the ROM 39 are loaded into amain memory of the CPU 40.

Next, a description will be given, with reference to FIG. 2, of a datamanagement information obtaining process performed in the optical discdevice 20. FIG. 2 shows a flowchart corresponding to a series ofprocessing algorithms executed by the CPU 40. The present embodimentsets forth an example where a host device makes a request for obtainingtrack information (the number of tracks and an address of a specifiedtrack) in a recording area of the optical disc 15. Besides, a filesystem of the optical disc 15 conforms to a sequential UDF (UniversalDisc Format) standard.

In this example, the recording area of the optical disc 15 includes Nsessions (3=<N=<191), where a session 1 is an innermost session, and asession N is an outermost session. Additionally, each of the session 1to a session (N−1) is a close session for which a recording of data iscompleted, and the session N is an open session for which a recording ofdata is not completed. Further, in the session N, data is recorded ineach of M fragments (M<16).

Also in this example, it is assumed that a session disc control block(SDCB) recorded in a lead-in (or an Intro) area of the session N isalready copied to the RAM 41. This SDCB (hereinafter referred to as“SDCB of the session N”) stores information which includes a sessionnumber of the session N, session information (a session number, a startaddress and a final address of each session) of each of the session 1 tothe session (N−1), and fragment information (fragment numbers, and astart address and a final address of each fragment) in the session N.

In step 401 shown in FIG. 2, it is judged whether or not a host devicemakes a request for obtaining the number of tracks. In this example,since the host device makes the request for obtaining the number oftracks, the judgment in the step 401 is affirmative, and the processtransits to step 403.

In the step 403, the SDCB of the session N stored in the RAM 41 isreferred to, and the number of close sessions in the recording area(hereinafter referred to as “close session number CS”) is obtained fromthe session number of the session N. More specifically, since thesession numbers are allocated sequentially from the innermost session inthe recording area, the session number of the session N is larger by onethan the close session number CS in the recording area. That is, theclose session number CS can be obtained by subtracting one from thesession number of the session N.

In step 405, the SDCB of the session N stored in the RAM 41 is referredto, and the number of fragments in the open session N (hereinafterreferred to as “fragment number OSF”) is obtained.

In step 407, regarding each of the close sessions as a pseudo track, aresponse track number AT is obtained as a response to the request forobtaining the number of tracks, according to the following expression(1).AT=CS+OSF  (1)

In step 409, the response track number AT obtained according to theforegoing expression (1) is communicated to the host device. Then, theprocess transits to step 415. In the present first embodiment, since theclose session number CS equals (N−1), and the fragment number OSF in theopen session N equals M, the response track number AT equals (N−1+M).Besides, when there is no open session, the fragment number OSF equals0.

On the other hand, in the step 401, when the host device does not makethe request for obtaining the number of tracks, the judgment in the step401 is negative, and the process transits to the step 415.

In the step 415, it is judged whether or not the host device makes arequest for obtaining an address of a specified track. In this example,since the host device makes the request for obtaining the address of thespecified track, the judgment in the step 415 is affirmative, and theprocess transits to step 417.

In the step 417, by comparing a track number of the specified track(hereinafter referred to as “specified track number”) with the closesession number CS, it is judged whether or not the specified tracknumber is equal to or smaller than the close session number CS. In otherwords, it is judged whether the specified track is a pseudo track or atrack in the open session N. When the specified track is a pseudo track,i.e., when the specified track number is equal to or smaller than theclose session number CS, the judgment in the step 417 is affirmative,and the process transits to step 419. Besides, in the present firstembodiment, the specified track number is P.

In the step 419, the SDCB of the session N stored in the RAM 41 isreferred to, and a start address of a session P is extracted. Then,according to the start address of the session P an SDCB of the session Precorded in the recording area of the optical disc 15 is retrieved, anda start address of a first fragment in the session P and a final addressof a last fragment in the session P are obtained. Then, the startaddress of the first fragment in the session P is assumed to be a startaddress of the specified track P, and the final address of the lastfragment in the session P is assumed to be a final address of thespecified track P. Thus, address information of the pseudo track isassumed to be address information of the specified track.

In the step 417, on the other hand, when the specified track is a trackin the open session N, i.e., when the specified track number P exceedsthe close session number CS, the judgment in the step 417 is negative,and the process transits to step 425.

In the step 425, a fragment number FN corresponding to the specifiedtrack number P is obtained according to the following expression (2).FN=P−CS−1+OSM1  (2)

“OSM1” in the foregoing expression (2) is a first fragment number in theopen session N, which can be obtained by referring to the fragmentinformation of the open session N recorded in the RAM 41. Besides,fragment numbers are allocated sequentially from a first fragment in thesession 1. That is, fragment numbers and session numbers are irrelevant.

In step 427, the fragment information of the open session N recorded inthe RAM 41 is referred to, and a start address of a fragment of thefragment number FN (hereinafter referred to as “fragment FN”) is assumedto be a start address of the specified track P, and a final address ofthe fragment FN is assumed to be a final address of the specified trackP.

In step 431, the address information of the specified track P obtainedas above is communicated to the host device. Then, the data managementinformation obtaining process is ended.

Next, a description will be given of a processing operation of theoptical disc device 20 for reproducing data recorded on the optical disc15.

When the optical disc 15 is inserted (mounted) into a predeterminedposition of the optical disc device 20, the CPU 40 obtains informationconcerning close sessions recorded on a predetermined position in therecording area of the optical disc 15. According to this information,the CPU 40 extracts an address of a last close session, and checkswhether or not an open session follows the last close session. When anopen session follows the last close session, the CPU 40 reads an SDCB ofthe open session, and copies the SDCB of the open session to the RAM 41.When no open session follows the last close session, the CPU 40 reads anSDCB of the last close session, and copies the SDCB of the last closesession to the RAM 41.

Upon receiving a request from a host device for obtaining trackinformation, the CPU 40 imparts a response to the host device, asdescribed above with reference to FIG. 2.

Upon receiving a request from a host device for reproducing data with aspecified track, the CPU 40 obtains address information of the specifiedtrack in the recording area of the optical disc 15, and reads a startaddress of the specified track. The CPU 40 regards this start address ofthe specified track as a read start position for reading data.

Then, the CPU 40 supplies the motor driver 27 with a control signal forcontrolling the revolution of the spindle motor 22 according to areproducing rate, and also informs the reproduction signal processingcircuit 28 of the reception of the request from the host device forreproducing data. When the revolution of the optical disc 15 reaches apredetermined linear velocity, an output signal (an electric currentsignal) is supplied from the optical pickup 23 to the reproductionsignal processing circuit 28.

According to the output signal supplied from the optical pickup 23, thereproduction signal processing circuit 28 obtains position information,and informs the CPU 40 of this position information. Further, accordingto the output signal supplied from the optical pickup 23, thereproduction signal processing circuit 28 detects a focus error signaland a track error signal, and supplies the focus error signal and thetrack error signal to the servo controller 33. According to the focuserror signal and the track error signal supplied from the reproductionsignal processing circuit 28, the servo controller 33 causes the motordriver 27 to drive the focusing actuator and the tracking actuator ofthe optical pickup 23 and correct a focusing error and a tracking error.

According to the position information supplied from the reproductionsignal processing circuit 28, the CPU 40 supplies the motor driver 27with a signal for directing an seek operation so as to position theoptical pickup 23 at the read start position.

According to the position information supplied from the reproductionsignal processing circuit 28, the CPU 40 checks whether or not theoptical pickup 23 is positioned at the read start position. When the CPU40 judges that the optical pickup 23 is positioned at the read startposition, the CPU 40 informs the reproduction signal processing circuit28 of this judgment. Then, according to the output signal supplied fromthe optical pickup 23, the reproduction signal processing circuit 28detects an RF signal. After applying processes, such as an errorcorrection process, to the RF signal, the reproduction signal processingcircuit 28 stores the RF signal (reproduction data) in the buffer RAM34. Besides, until the completion of the reproducing process, thereproduction signal processing circuit 28 detects the focus error signaland the track error signal according to the output signal supplied fromthe optical pickup 23, as described above, and corrects a focusing errorand a tracking error as needed via the servo controller 33 and the motordriver 27.

When the reproduction data stored in the buffer RAM 34 amounts to sectordata, the buffer manager 37 transfers the reproduction data as thesector data to the host device via the interface 38.

As described above, in the optical disc device 20 according to thepresent first embodiment, the CPU 40 forms a pseudo area setting partfor regarding each of close sessions as a pseudo track, a managementinformation obtaining part for obtaining management information(including track information), and an informing part for informing ahost device of the obtained management information.

Additionally, in the optical disc device 20 according to the presentfirst embodiment, the data management information obtaining processshown in FIG. 2 performed by the CPU 40 is stored in the ROM 39 as thedata management information obtaining program.

Further, in the optical disc device 20 according to the present firstembodiment, the CPU 40 performs a data management information obtainingmethod by executing the data management information obtaining processaccording to the data management information obtaining program.

As described above, in the data management information obtaining methodaccording to the present first embodiment, in response to a request froma host device for obtaining the number of tracks, the number of tracksis calculated with regarding each of the close sessions included in therecording area as a pseudo track. Therefore, the number of pseudo trackscan be immediately obtained simply by referring to the session numberrecorded in the SDCB of the last session (the open session N in thepresent first embodiment). That is, since there is no need for countingthe number of all tracks (fragments) in the recording area, therequested information can be obtained quickly in response to the requestfor obtaining the number of tracks, compared to a conventional opticaldisc device.

Additionally, in the present first embodiment, the number of pseudotracks, i.e., the number of close sessions, is obtained as a response tothe request for obtaining the number of tracks. Therefore, there is noneed for examining SDCBs of all of the sessions, and the number ofpseudo tracks can be immediately obtained according only to the SDCB ofthe last session. Thus, the requested information can be obtainedquickly in response to the request for obtaining the number of tracks.Besides, recording data on a recordable information recording mediumnecessitates information concerning tracks existing in the open session.However, information concerning tracks existing in the close sessions,on which data cannot be recorded, is not important for the datarecording. Therefore, there is no inconvenience in responding the numberof close sessions to the request for obtaining the number of tracks.

Further, in the present first embodiment, the sum of the number ofpseudo tracks and the number of tracks in the open session N is obtainedas a response to the request for obtaining the number of tracks.Conventionally, in order to count the number of tracks, SDCBs of all ofthe sessions need to be examined, which consumes a long time because theSDCBs of the sessions are distributed in the recording area. However, inthe present first embodiment, since there is no need for counting thenumber of tracks in the close sessions, the requested information can beobtained quickly in response to the request for obtaining the number oftracks, compared to a conventional optical disc device.

Besides, in the present first embodiment, the start address of a firsttrack in a close session corresponding to the track number of thespecified track and the final address of a last track in the closesession, i.e., the start address and the final address of the pseudotrack corresponding to the track number of the specified track, areobtained as a response to a request for obtaining the address of thespecified track. In this course, since the start address of the firsttrack in the close session and the final address of the last track inthe close session can be obtained in a short time, the requestedinformation can be obtained quickly in response to the request forobtaining the address of the specified track, compared to a conventionaloptical disc device. Besides, recording data on a recordable informationrecording medium necessitates accurate address information of tracksexisting in the open session. However, data is recorded sequentially,and no more data is to be recorded in the close sessions; therefore,there is substantially no practical advantage in responding accurateaddress information of tracks in the close sessions.

Additionally, in the present first embodiment, regarding each of theclose sessions as a pseudo track reduces a maximum number of tracks to206 {=190 (the number of pseudo tracks)+16 (the number of tracks in theopen session)}. Therefore, information of each of these tracks can beretained in the RAM 41.

Further, in the optical disc device 20 according to the present firstembodiment, in response to a request from a host device for obtainingtrack information, an area (a close session) including a plurality oftracks is regarded as a pseudo track to the extent that the requestedinformation is not adversely influenced; accordingly, unnecessaryinformation does not have to be obtained in response to the request fromthe host device. Therefore, the request from the host device forobtaining the track information can be responded in a short time.

<<Embodiment 2>>

Next, a description will be given, with reference to FIG. 3 to FIG. 6,of a second embodiment according to the present invention.

The present second embodiment has a data management informationobtaining process different from the data management informationobtaining process according to the foregoing first embodiment.Specifically, only the data management information obtaining programstored in the ROM 39 includes differences from the foregoing firstembodiment; other than this respect, the optical disc device 20according to the present second embodiment has the same configuration asin the foregoing first embodiment. Accordingly, the followingdescription will be made mainly for the differences from the foregoingfirst embodiment, and elements that are identical or equivalent to theelements described in the foregoing first embodiment are referenced bythe same reference marks, and will not be described in detail.

Thus, the description will be given, with reference to FIG. 3 to FIG. 6,of the data management information obtaining process performed in theoptical disc device 20 comprising the ROM 39 storing the data managementinformation obtaining program according to the present secondembodiment. FIG. 3 to FIG. 6 show flowcharts corresponding to a seriesof processing algorithms executed by the CPU 40. The present secondembodiment sets forth an example where a host device makes a request forobtaining session information (the number of sessions) and trackinformation (the number of tracks and an address of a specified track)in the recording area of the optical disc 15. Besides, the optical disc15 meets the same preconditions as in the foregoing first embodiment.

In step 501 shown in FIG. 3, it is judged whether or not a host devicemakes a request for obtaining the number of sessions in the recordingarea of the optical disc 15. In this example, since the host devicemakes the request for obtaining the number of sessions, the judgment inthe step 501 is affirmative, and the process transits to step 503.

In the step 503, a process for obtaining the number of sessions isperformed. Here, a description will be given, with reference to FIG. 4,of the process for obtaining the number of sessions.

In step 601 shown in FIG. 4, the SDCB of the session N recorded in theRAM 41 is referred to, and the number of all of sessions in therecording area (hereinafter referred to as “overall session number AS”)is obtained. More specifically, the session number of the session Nrecorded in the RAM 41 is obtained as the overall session number AS.

In step 603, it is judged whether or not the overall session number ASexceeds “1”. In this example, since the overall session number ASexceeds “1”, the judgment in the step 603 is affirmative, and theprocess transits to step 605.

In the step 605, (N−2) sessions from the session 1 to the session (N−2)are regarded as one pseudo session. Then, since the recording areaincludes a total of two close sessions, i.e., the above-mentioned pseudosession and the session (N−1), the number of pseudo close sessions(hereinafter referred to as “pseudo close session number SS”) is set to“2”.

In step 607, it is judged whether or not an open session exists in therecording area. Specifically, by referring to the SDCB of the session Nrecorded in the RAM 41, and checking whether the session N is an opensession or a close session, it can be judged whether or not an opensession exists in the recording area. In this example, since an opensession exists in the recording area, the judgment in the step 607 isaffirmative, and the process transits to step 609.

In the step 609, the number of response sessions (hereinafter referredto as “response session number RS”) is calculated as a response to therequest from the host device for obtaining the number of sessions,according to the following expression (3). Specifically, the responsesession number RS becomes a value (=3) obtained by adding the number ofthe open session (=1) to the pseudo close session number SS. Then, theprocess for obtaining the number of sessions is ended.RS=SS+1  (3)

On the other hand, in the step 607, when an open session does not existin the recording area, i.e., when the session N is not an open session,the judgment in the step 607 is negative, and the process transits tostep 611.

In the step 611, the response session number RS is calculated accordingto the following expression (4). Specifically, the response sessionnumber RS becomes a value identical to the pseudo close session numberSS. Then, the process for obtaining the number of sessions is ended.RS=SS  (4)

On the other hand, in step 603, when the overall session number AS is“1”, i.e, when only one session exists in the recording area, thejudgment in the step 603 is negative, and the process transits to step613.

In the step 613, since only one session exists in the recording area,the pseudo close session number SS is set to “1”. Then, the processtransits to step 611.

In step 505 shown in FIG. 3, the response session number RS obtained bythe process for obtaining the number of sessions is communicated to thehost device. Then, the process transits to step 507.

On the other hand, in the step 501, when the host device does not makethe request for obtaining the number of sessions, the judgment in thestep 501 is negative, and the process transits to the step 507.

In the step 507, it is judged whether or not the host device makes arequest for obtaining the number of tracks in the recording area. Inthis example, since the host device makes the request for obtaining thenumber of tracks, the judgment in the step 507 is affirmative, and theprocess transits to step 509.

In the step 509, a process for obtaining the number of tracks isperformed. Here, a description will be given, with reference to FIG. 5,of the process for obtaining the number of tracks.

In step 621 shown in FIG. 5, it is judged whether or not an open sessionexists in the recording area. In this example, since an open sessionexists in the recording area, the judgment in the step 621 isaffirmative, and the process transits to step 623.

In the step 623, the fragment information of the session N recorded inthe RAM 41 is referred to, and the number of fragments in the opensession N (“fragment number OSF”) is obtained.

In step 625, the number of response tracks (“response track number AT”)is obtained as a response to the request from the host device forobtaining the number of tracks, according to the following expression(5). Specifically, regarding the pseudo (close) session and the lastclose session as pseudo tracks, the response track number AT iscalculated.AT=SS+OSF  (5)

In the present second embodiment, since the pseudo close session numberSS equals “2”, and the fragment number OSF in the open session N equalsM, the response track number AT equals (M+2). Then, the process forobtaining the number of tracks is ended.

On the other hand, in the step 621, when an open session does not existin the recording area, the judgment in the step 621 is negative, and theprocess transits to step 627.

In the step 627, the response track number AT is calculated according tothe following expression (6). Specifically, the response track number ATbecomes a value identical to the pseudo close session number SS. Then,the process for obtaining the number of tracks is ended.AT=SS  (6)

In step 511 shown in FIG. 3, the response track number AT obtained bythe process for obtaining the number of tracks is communicated to thehost device. Then, the process transits to step 513.

On the other hand, in the step 507, when the host device does not makethe request for obtaining the number of tracks, the judgment in the step507 is negative, and the process transits to the step 513.

In the step 513, it is judged whether or not the host device makes arequest for obtaining address information of a specified track. In thisexample, since the host device makes the request for obtaining theaddress information of the specified track, the judgment in the step 513is affirmative, and the process transits to step 515. Besides, the hostdevice specifies the above-mentioned specified track by a track number(“specified track number”), as in the foregoing first embodiment.

In the step 515, a process for obtaining the address information isperformed. Here, a description will be given, with reference to FIG. 6,of the process for obtaining the address information.

In step 651 shown in FIG. 6, by comparing the specified track numberwith the pseudo close session number SS, it is judged whether or not thespecified track number is equal to or smaller than the pseudo closesession number SS. In other words, it is judged whether the specifiedtrack is a pseudo track (the pseudo session or the last close session)or a track in the open session N. When the specified track is a pseudotrack, i.e., when the specified track number is equal to or smaller thanthe pseudo close session number SS, the judgment in the step 651 isaffirmative, and the process transits to step 653. Besides, in thepresent second embodiment, the specified track number is P, as anexample.

In the step 653, it is judged whether or not the specified track numberP is “1”. In other words, it is judged whether the specified track isthe pseudo session or the last close session. When the specified trackis the pseudo session, i.e., when the specified track number P is “1”,the judgment in the step 653 is affirmative, and the process transits tostep 655.

In the step 655, the SDCB of the session N stored in the RAM 41 isreferred to, and a start address of the session 1 and a final address ofthe session (N−2) are obtained. Then, the start address of the session 1is assumed to be a start address of the specified track P, and the finaladdress of the session (N−2) is assumed to be a final address of thespecified track P. Then, the process for obtaining the addressinformation is ended.

On the other hand, in the step 653, when the specified track is the lastclose session, i.e., when the specified track number P is “2”, thejudgment in the step 653 is negative, and the process transits to step657.

In the step 657, the SDCB of the session N stored in the RAM 41 isreferred to, and a start address of a first fragment in the session(N−1), i.e., the last close session, and a final address of a lastfragment in the session (N−1) are obtained. Then, the start address ofthe first fragment in the session (N−1) is assumed to be a start addressof the specified track P, and the final address of the last fragment inthe session (N−1) is assumed to be a final address of the specifiedtrack P. Then, the process for obtaining the address information isended.

On the other hand, in the step 651, when the specified track is a trackin the open session N, i.e., when the specified track number P exceedsthe pseudo close session number SS, the judgment in the step 651 isnegative, and the process transits to step 659.

In the step 659, a fragment number FN corresponding to the specifiedtrack number P is obtained according to the following expression (7).FN=P−SS−1+OSM1  (7)

In step 661, a start address of a fragment of the fragment number FN(“fragment FN”) is assumed to be a start address of the specified trackP, and a final address of the fragment FN is assumed to be a finaladdress of the specified track P. Then, the process for obtaining theaddress information is ended.

In step 517 shown in FIG. 3, the start address and the final address ofthe specified track P obtained by the process for obtaining the addressinformation is communicated to the host device. Then, the datamanagement information obtaining process is ended.

In the optical disc device 20 according to the present secondembodiment, data recorded on the optical disc 15 is reproduced accordingto a request from a host device for reproducing data with a specifiedtrack, as in the foregoing first embodiment.

As described above, in the optical disc device 20 according to thepresent second embodiment, the data management information obtainingprocess including the processes shown in FIG. 3 to FIG. 6 performed bythe CPU 40 is stored in the ROM 39 as the data management informationobtaining program.

Additionally, in the optical disc device 20 according to the presentsecond embodiment, the CPU 40 performs a data management informationobtaining method by executing the data management information obtainingprocess according to the above-mentioned data management informationobtaining program.

As described above, in the data management information obtaining methodaccording to the present second embodiment, in response to a requestfrom a host device for obtaining the number of sessions, close sessionsexcept at least the last close session among the close sessions includedin the recording area are regarded as one session. Latest fileinformation of recorded data is recorded at a predetermined position inthe last close session; therefore, even when the close sessions exceptthe last close session are regarded as one pseudo session, theabove-mentioned latest file information recorded in the last closesession can be read accurately. Especially, on a recordable informationrecording medium, data is recorded sequentially; therefore, regardingthe close sessions except the last close session as one pseudo sessioncauses no inconvenience in responding to the request for obtaining thenumber of sessions.

Additionally, in the present second embodiment, when the recording areaof the optical disc 15 includes a plurality of close sessions and anopen session, the number of sessions is responded as “3” to the requestfor obtaining the number of sessions; and when the recording area of theoptical disc 15 includes only a plurality of close sessions, the numberof sessions is responded as “2” to the request for obtaining the numberof sessions. That is, a value obtained by adding “1” to the number ofsessions excluded from the pseudo session among the sessions included inthe recording area of the optical disc 15 is obtained as a response tothe request for obtaining the number of sessions. Thus, there is no needfor counting the number of sessions in the recording area; thissimplifies the process for obtaining the number of sessions, compared toa conventional optical disc device. Accordingly, the requestedinformation can be obtained quickly in response to the request forobtaining the number of sessions.

Additionally, in the present second embodiment, all tracks included inthe close sessions except the last close session are regarded as onepseudo track in obtaining a response to a request for obtaining thenumber of tracks. Accordingly, the number of tracks in the pseudo trackdoes not have to be counted; this simplifies the process for obtainingthe number of tracks, compared to a conventional optical disc device.Accordingly, the requested information can be obtained quickly inresponse to the request for obtaining the number of tracks.

Additionally, in the present second embodiment, when the recording areaof the optical disc 15 includes only a plurality of close sessions, thenumber of tracks is responded as “2” to the request for obtaining thenumber of tracks; and when the recording area of the optical disc 15includes a plurality of close sessions and an open session, the numberof tracks is responded as the number of tracks in the open session plus“2” to the request for obtaining the number of tracks. This simplifiesthe process for obtaining the number of tracks. Accordingly, therequested information can be obtained quickly in response to the requestfor obtaining the number of tracks, compared to a conventional opticaldisc device. Besides, an Intro and a Closure of each session include asector ID thereof as a user data attribute; further, a logical addressis allocated thereto. Accordingly, regarding a plurality of closesessions as one close session causes no inconvenience for a normalreproduction of data.

Besides, in the present second embodiment, in response to a request forobtaining address information of a specified track, all tracks includedin the close sessions except the last close session are regarded as onepseudo track, and the start address of a first track in the pseudo trackand the final address of a last track in the pseudo track are obtainedas the response to the request for obtaining the address information ofthe specified track. Consequently, the requested information can beobtained quickly in response to the request for obtaining the addressinformation, compared to a conventional optical disc device. Besides,even when the tracks included in the close sessions except the lastclose session are regarded as one pseudo track, the Intro and theClosure of each session can be recognized accurately; therefore, theresponse obtained as above exerts no adverse effect upon reproduction ofdata.

As described above, regarding the close sessions except at least thelast close session as one session or one track can simplify theprocesses concerning sessions and tracks. For example, when the closesessions except the last close session are regarded as one pseudosession, the number of sessions for the host device becomes “3” {(thepseudo session)+(the last close session)+(the open session)} at themaximum. Additionally, for example, when the close sessions except thelast close session are regarded as one pseudo track, and also when thelast close session is regarded as one pseudo track, the number of tracksfor the host device becomes “18” {(the number of pseudo tracks=2)+(thenumber of tracks in the open session=16)} at the maximum.

Further, in the optical disc device 20 according to the present secondembodiment, in response to a request from a host device for obtainingdata management information, an area (close sessions) including aplurality of tracks is regarded as a pseudo track to the extent that therequested information is not adversely influenced; accordingly,unnecessary information does not have to be obtained in response to therequest from the host device. Therefore, the request from the hostdevice for obtaining the session information and the track informationcan be responded in a short time.

Besides, in the present second embodiment, the close sessions exceptonly the last close session among the close sessions included in therecording area are regarded as a pseudo session; however, the presentinvention is not limited thereto. For example, close sessions exceptother close sessions including the last close session may be regarded asa pseudo session.

Further, in the present second embodiment, the last close session isdistinguished from the close sessions except the last close session insetting one pseudo session or one pseudo track; however, when therecording area of the optical disc 15 includes an open session, and theoptical disc device 20 can reproduce data recorded in the open session,the last close session does not necessarily have to be distinguishedfrom the close sessions except the last close session.

Additionally, in the present second embodiment, the recording areaincludes at least one close session; however, the recording area mayinclude only the open session. In this case, neither the pseudo sessionnor the pseudo track is set. Additionally, in the step 625 shown in FIG.5, the CPU 40 calculates the response track number AT according to thefollowing expression (8) in place of the foregoing expression (5).AT=OSF  (8)

Further, in the above-mentioned case, the CPU 40 performs the processfor obtaining the address information shown in FIG. 6, with the pseudoclose session number SS being zero.

Additionally, in the foregoing embodiments, the CPU 40 reads an SDCB ofthe open session or the last close session, and copies the SDCB to theRAM 41, when the optical disc 15 is inserted into a predeterminedposition of the optical disc device 20; however, the CPU 40 may read theSDCB upon receiving a request from a host device for obtaining datamanagement information.

Besides, in the optical disc device 20 according to the foregoingembodiments, the data management information obtaining program is storedin the ROM 39; however, the data management information obtainingprogram may be stored in other information recording media (a CD-ROM, amagneto-optical disc, an MO, etc.), as long as the data managementinformation obtaining program can be loaded into the main memory of theCPU 40.

Additionally, in the foregoing embodiments, a DVD+R is used as theoptical disc 15; however, the optical disc 15 may be replaced by otherinformation recording media on which data is recorded on a plurality ofdivided data areas, such as sessions or tracks, in a recording areathereof.

Further, the optical disc device 20 according to the foregoingembodiments may be provided in a same body incorporating the hostdevice, or may be provided in a different body not incorporating thehost device.

Additionally, in the foregoing embodiments, the optical disc device isused as the information reproducing device; however, other informationreproducing devices may be used as long as the information reproducingdevices can reproduce data from information recording media on whichdata is recorded on a plurality of divided data areas, such as sessionsor tracks, in a recording area thereof. Further, these informationrecording/reproducing devices may not only reproduce but also recorddata.

The present invention is not limited to the specifically disclosedembodiments, and variations and modifications may be made withoutdeparting from the scope of the present invention.

The present application is based on Japanese priority applications No.2001-385652 filed on Dec. 19, 2001, and No. 2001-393643 filed on Dec.26, 2001, the entire contents of which are hereby incorporated byreference.

1. A data management information obtaining method for obtaining datamanagement information concerning a recording of data recorded on eachof data areas divided in a recording area of an information recordingmedium as a response to a request for obtaining the data managementinformation, the method comprising: the step of obtaining said datamanagement information including information concerning a plurality ofpredetermined data areas among said data areas as information concerninga predetermined pseudo area in response to said request for obtainingsaid data management information, wherein said recording area includesat least one session including tracks as said data areas, and said datamanagement information includes at least one of a number of the sessionsincluded in said recording area, a number of the tracks included in saidrecording area, and a track address indicating a recording position ofeach of the tracks specified by a track number, and wherein said requestfor obtaining said data management information includes a request forobtaining said number of said tracks, and said number of said tracks iscalculated in response to said request for obtaining said number of saidtracks by regarding at least one close session for which the recordingof the data is completed among said sessions included in said recordingarea as a pseudo track, the pseudo track being said predetermined pseudoarea.
 2. The data management information obtaining method as claimed inclaim 1, wherein a number of the pseudo tracks forms the number of thetracks as a response to said request for obtaining said number of saidtracks.
 3. The data management information obtaining method as claimedin claim 1, wherein said recording area includes a plurality of thesessions including the close session for which the recording of the datais completed and an open session for which the recording of the data isnot completed, and a sum of a number of the pseudo tracks and a numberof tracks in said open session forms the number of the tracks as aresponse to said request for obtaining said number of said tracks.
 4. Adata management information obtaining method for obtaining datamanagement information concerning a recording of data recorded on eachof data areas divided in a recording area of an information recordingmedium as a response to a request for obtaining the data managementinformation, the method comprising: the step of obtaining said datamanagement information including information concerning a plurality ofpredetermined data areas among said data areas as information concerninga predetermined pseudo area which comprises at least one of said dataareas in response to said request for obtaining said data managementinformation, wherein said recording area includes at least one sessionincluding tracks as said data areas, and said data managementinformation includes at least one of a number of the sessions includedin said recording area, a number of the tracks included in saidrecording area, and a track address indicating a recording position ofeach of the tracks specified by a track number, and wherein said requestfor obtaining said data management information includes a request forobtaining said track address, at least one close session for which therecording of the data is completed among said sessions included in saidrecording area is regarded as a pseudo track, the pseudo track beingsaid predetermined pseudo area, and a start address of a first track anda final address of a last track in the pseudo track corresponding tosaid track number specified by said request for obtaining said trackaddress forms the track address as a response to said request forobtaining said track address.
 5. A data management information obtainingmethod for obtaining data management information concerning a recordingof data recorded on each of data areas divided in a recording area of aninformation recording medium as a response to a request for obtainingthe data management information, the method comprising: the step ofobtaining said data management information including informationconcerning a plurality of predetermined data areas among said data areasas information concerning a predetermined pseudo area which comprises atleast one of said data areas in response to said request for obtainingsaid data management information, wherein said recording area includesat least one session including tracks as said data areas, and said datamanagement information includes at least one of a number of the sessionsincluded in said recording area, a number of the tracks included in saidrecording area, and a track address indicating a recording position ofeach of the tracks specified by a track number, and wherein saidrecording area includes a plurality of the sessions, and said requestfor obtaining said data management information includes a request forobtaining said number of said sessions, and said number of said sessionsis calculated in response to said request for obtaining said number ofsaid sessions by regarding close sessions except at least a last closesession as one pseudo session among all of close sessions included insaid recording area for each of which the recording of the data iscompleted, the pseudo session being said predetermined pseudo area. 6.The data management information obtaining method as claimed in claim 5,wherein the number of the sessions as a response to said request forobtaining said number of said sessions is 3 when said plurality of saidsessions include a plurality of the close sessions for which therecording of the data is completed and an open session for which therecording of the data is not completed, and the number of the sessionsas the response to said request for obtaining said number of saidsessions is 2 when said plurality of said sessions include only theplurality of the close sessions.
 7. A data management informationobtaining method for obtaining data management information concerning arecording of data recorded on each of data areas divided in a recordingarea of an information recording medium as a response to a request forobtaining the data management information, the method comprising: thestep of obtaining said data management information including informationconcerning a plurality of predetermined data areas among said data areasas information concerning a predetermined pseudo area which comprises atleast one of said data areas in response to said request for obtainingsaid data management information, wherein said recording area includesat least one session including tracks as said data areas, and said datamanagement information includes at least one of a number of the sessionsincluded in said recording area, a number of the tracks included in saidrecording area, and a track address indicating a recording position ofeach of the tracks specified by a track number, and wherein saidrecording area includes a plurality of the sessions, and said requestfor obtaining said data management information includes a request forobtaining said number of said tracks, and said number of said tracks iscalculated in response to said request for obtaining said number of saidtracks by regarding all tracks in close sessions except at least a lastclose session as one pseudo track among all of close sessions includedin said recording area for each of which the recording of the data iscompleted, the pseudo track being said predetermined pseudo area.
 8. Thedata management information obtaining method as claimed in claim 7,wherein said plurality of said sessions include only a plurality of theclose sessions, and the number of the tracks as a response to saidrequest for obtaining said number of said tracks is
 2. 9. The datamanagement information obtaining method as claimed in claim 7, whereinsaid plurality of said sessions include a plurality of the closesessions for which the recording of the data is completed and an opensession for which the recording of the data is not completed, and thenumber of the tracks as a response to said request for obtaining saidnumber of said tracks is a number of tracks in said open session plus 2.10. A data management information obtaining method for obtaining datamanagement information concerning a recording of data recorded on eachof data areas divided in a recording area of an information recordingmedium as a response to a request for obtaining the data managementinformation, the method comprising: the step of obtaining said datamanagement information including information concerning a plurality ofpredetermined data areas among said data areas as information concerninga predetermined pseudo area which comprises at least one of said dataareas in response to said request for obtaining said data managementinformation, wherein said recording area includes at least one sessionincluding tracks as said data areas, and said data managementinformation includes at least one of a number of the sessions includedin said recording area, a number of the tracks included in saidrecording area, and a track address indicating a recording position ofeach of the tracks specified by a track number, and wherein saidrecording area includes a plurality of the sessions, and said requestfor obtaining said data management information includes a request forobtaining said track address, all tracks in close sessions except atleast a last close session among all of close sessions included in saidrecording area for each of which the recording of the data is completedare regarded as one pseudo track, the pseudo track being saidpredetermined pseudo area, and a start address of a first track and afinal address of a last track in said pseudo track forms the trackaddress as a response to said request for obtaining said track address.11. An information reproducing device reproducing data from aninformation recording medium including a recording area divided in aplurality of data areas on each of which the data is recorded, thedevice comprising: a pseudo area setting part setting a plurality ofpredetermined data areas among said data areas as a predetermined pseudoarea in response to a request from an external device for obtaining datamanagement information concerning a recording of said data recorded oneach of said data areas; a management information obtaining partobtaining said data management information including informationconcerning said predetermined pseudo area; and an informing partinforming said external device of said data management information as aresponse to said request for obtaining said data management information.12. The information reproducing device as claimed in claim 11, whereinsaid recording area includes at least one session including tracks assaid data areas, and said data management information includes at leastone of a number of the sessions included in said recording area, anumber of the tracks included in said recording area, and a trackaddress indicating a recording position of each of the tracks specifiedby a track number.
 13. The information reproducing device as claimed inclaim 12, wherein said request for obtaining said data managementinformation includes a request for obtaining said number of said tracks,said pseudo area setting part sets at least one close session for whichthe recording of the data is completed among said sessions included insaid recording area as a pseudo track in response to said request forobtaining said number of said tracks, the pseudo track being saidpredetermined pseudo area, and said management information obtainingpart obtains a number of the pseudo tracks as the number of the tracksincluded in said data management information.
 14. The informationreproducing device as claimed in claim 13, wherein said recording areaincludes a plurality of the sessions including the close session forwhich the recording of the data is completed and an open session forwhich the recording of the data is not completed, and said managementinformation obtaining part obtains a sum of said number of said pseudotracks and a number of tracks in said open session as the number of thetracks included in said data management information.
 15. The informationreproducing device as claimed in claim 12, wherein said request forobtaining said data management information includes a request forobtaining said track address, said pseudo area setting part sets atleast one close session for which the recording of the data is completedamong said sessions included in said recording area as a pseudo track inresponse to said request for obtaining said track address, the pseudotrack being said predetermined pseudo area, and said managementinformation obtaining part obtains a start address of a first track anda final address of a last track in the pseudo track corresponding tosaid track number specified by said request for obtaining said trackaddress as the track address included in said data managementinformation.
 16. The information reproducing device as claimed in claim12, wherein said recording area includes a plurality of the sessions,and said request for obtaining said data management information includesa request for obtaining said number of said sessions, said pseudo areasetting part sets close sessions except at least a last close session asone pseudo session among all of close sessions included in saidrecording area for each of which the recording of the data is completed,in response to said request for obtaining said number of said sessions,the pseudo session being said predetermined pseudo area, and saidmanagement information obtaining part obtains a value obtained by adding1 to a number of sessions excluded from said pseudo session among saidplurality of said sessions as the number of the sessions included insaid data management information.
 17. The information reproducing deviceas claimed in claim 12, wherein said recording area includes a pluralityof the sessions, and said request for obtaining said data managementinformation includes a request for obtaining said number of said tracks,said pseudo area setting part sets all tracks in close sessions exceptat least a last close session as one pseudo track among all of closesessions included in said recording area for each of which the recordingof the data is completed, in response to said request for obtaining saidnumber of said tracks, the pseudo track being said predetermined pseudoarea, said management information obtaining part obtains a valueobtained by adding 1 to a number of sessions excluded from said pseudotrack among said plurality of said sessions as the number of the tracksincluded in said data management information when said plurality of saidsessions include only a plurality of the close sessions, and saidmanagement information obtaining part obtains a value obtained by adding1 to a sum of a number of close sessions excluded from said pseudo trackamong all of said close sessions and a number of tracks in an opensession as the number of the tracks included in said data managementinformation when said plurality of said sessions include a plurality ofthe close sessions for which the recording of the data is completed andthe open session for which the recording of the data is not completed.18. The information reproducing device as claimed in claim 12, whereinsaid recording area includes a plurality of the sessions, and saidrequest for obtaining said data management information includes arequest for obtaining said track address, said pseudo area setting partsets all tracks in close sessions except at least a last close sessionas one pseudo track among all of close sessions included in saidrecording area for each of which the recording of the data is completed,in response to said request for obtaining said track address, the pseudotrack being said predetermined pseudo area, and said managementinformation obtaining part obtains a start address of a first track anda final address of a last track in said pseudo track as the trackaddress included in said data management information.
 19. A computerreadable recording medium storing a data management informationobtaining program used in an information reproducing device reproducingdata from an information recording medium including a recording areadivided in a plurality of tracks composing at least one session, thedata being recorded on each of said tracks, so as to cause a controlcomputer of said information reproducing device to obtain datamanagement information concerning a recording of said data recorded oneach of said tracks, the recording medium comprising program code meansfor: regarding at least one close session for which the recording of thedata is completed among the sessions included in said recording area asa pseudo track in response to a request for obtaining a number of thetracks included in said recording area; and obtaining a number of thepseudo tracks as the number of the tracks as a response to said requestfor obtaining said number of said tracks.
 20. The computer readablerecording medium as claimed in claim 19, further comprising program codemeans for: obtaining a start address of a first track and a finaladdress of a last track in the pseudo track corresponding to a tracknumber as a track address as a response to a request for obtaining thetrack address indicating a recording position of each of the tracksspecified by said track number.
 21. A computer readable recording mediumstoring a data management information obtaining program used in aninformation reproducing device reproducing data from an informationrecording medium including a recording area divided in a plurality oftracks composing a plurality of sessions, the data being recorded oneach of said tracks, so as to cause a control computer of saidinformation reproducing device to obtain data management informationconcerning a recording of said data recorded on each of said tracks, therecording medium comprising program code means for: regarding closesessions except at least a last close session as one pseudo sessionamong all of close sessions included in said recording area for each ofwhich the recording of the data is completed, in response to a requestfor obtaining a number of the sessions included in said recording area;and obtaining a value obtained by adding 1 to a number of sessionsexcluded from said pseudo session among said plurality of said sessionsas the number of the sessions as a response to said request forobtaining said number of said sessions.
 22. The computer readablerecording medium as claimed in claim 21, further comprising program codemeans for: regarding said pseudo session as one pseudo track in responseto a request for obtaining a number of the tracks included in saidrecording area; and obtaining a value obtained by adding 1 to a numberof sessions excluded from said pseudo session among said plurality ofsaid sessions as the number of the tracks as a response to said requestfor obtaining said number of said tracks when said plurality of saidsessions include only a plurality of the close sessions, and obtaining avalue obtained by adding 1 to a sum of a number of sessions excludedfrom said pseudo session among all of said close sessions and a numberof tracks in an open session as the number of the tracks as the responseto said request for obtaining said number of said tracks when saidplurality of said sessions include a plurality of the close sessions forwhich the recording of the data is completed and the open session forwhich the recording of the data is not completed.
 23. The computerreadable recording medium as claimed in claim 21, further comprisingprogram code means for: obtaining a start address of a first track in afirst session of said pseudo session and a final address of a last trackin a last session of said pseudo session as a track address as aresponse to a request for obtaining the track address indicating arecording position of each of the tracks being specified.
 24. Thecomputer readable recording medium as claimed in claim 22, furthercomprising program code means for: obtaining a start address of a firsttrack in a first session of said pseudo session and a final address of alast track in a last session of said pseudo session as a track addressas a response to a request for obtaining the track address indicating arecording position of each of the tracks being specified.